1. Field of the Invention
The present invention relates to a laminated contact a probe for inspection of an ultra-microscopic pitch, and more particularly to a contact probe for use in a high frequency region, which probe is capable of closely examining the breaking down, short and the like of electrodes, patterns and the like of semiconductors, liquid crystals and the like, arranged at intervals of an ultra-microscopic pitch.
2. Description of the Related Art
Hitherto, there is adopted mainly a card type of contact probe for inspecting circuits such as a high-integrated circuit arranged at intervals of an ultra-microscopic pitch, an IC, a LSI and the like, in which a number of microscopic probe pins each having the bent tip are arranged in the form of an array in such a way that the probe pins come into contact with terminals of a high-integrated circuit.
With the remarkable advance of technology in the field of electronics, recently, there have been developed ultra-microscopic high-integrated circuits and the like provided with, for example, 60 .mu.m in pitch interval. However, the conventional card type of contact probe cannot cope with the inspection of such ultra-microscopic high-integrated circuits. To inspect the high-integrated circuits and the like provided with 60 .mu.m in pitch interval, there is a need to provide an arrangement in which the interval between the probe pin-to-pin is 60 .mu.m or below. However, according to the conventional card type of contact probe, since the adjacent probe pins cannot be subjected to an insulating coating treatment, it is obliged to provide an arrangement such that they are spaced so as not to contact with one another. Hence, a certain degree of interval has to be ensured, and it is the limit that the interval between the probe pin-to-pin is given with 120 .mu.m.
In order to perform an inspection for circuits of an integrated circuit arranged at intervals of a microscopic pitch, a plane-packaging device and the like for use in a high frequency region, it is necessary to provide such an arrangement that a circuit impedance is given with a desired value.
Hitherto, as a contact probe for high frequency region, there is known a coaxial probe in which a long and narrow wire-like shaped probe is centered, and a cylindrical ground is provided around the probe through a dielectric, so that the coaxial probe is shaped as a long and narrow cylinder in its entirety. Such a coaxial probe is in contact with a circuit to be measured through a connector, when the circuit is measured. Accordingly, such a type of coaxial probe is complicated in a structure and will be expensive. Further, for providing a contact probe for inspecting an integrated circuit arranged at intervals of a microscopic pitch, it involves a very difficult processing, and the mechanical strength would be reduced. Also a high frequency electrical loss will be increased. Furthermore, since the connector is interposed, there is associated with such a problem that it is difficult in regulation of the impedance.
According to the contact probe of the earlier development, in order to provide stretch properties with respect to the axis direction, there is a need to give a certain measure of strength on a tip needle portion. This causes the inductance to be increased, so that a transmission loss of the high frequency signals is increased. Interposing a coil spring makes it possible to reduce the tip needle portion. In this case, however, it is very difficult to implement a contact probe for inspection of a microscopic pitch. Further, interposing the coil spring involves such a problem that the high frequency electrical loss is increased.
In order to solve the above-mentioned problem, the applicant of the present application developed a contact probe formed with an ultra-thin plate. According to such a type of contact probe, in view of the fact that the ultra-thin plate is able to be formed with a thickness of not more than 60 .mu.m and also an insulating coating is readily implemented, it is possible to sufficiently cope with the ultra-microscopic high-integrated circuits and the like provided with an pitch interval of not more than 60 .mu.m.
Further, in order to provide for this type of probe characteristics of performing a circuit inspection for high frequency region, there is provided such an arrangement that an impedance can be set up to a desired value. On the other hand, the contact probe thus developed involves such a problem that the contact probe cannot cope with a large number of times of inspection, such as several hundred thousand times of inspection, since it is worse in elastic durability.